The lowest level of the ocean to which light can reach.
2.
The ambiguous region between two categories or states or conditions (usually containing some features of both). Synonym:no man's land."In the twilight zone between humor and vulgarity" , "In that no man's land between negotiation and aggression"
... us for an instant, and their motors were driven to their highest capacity. Fortunately, Ala's vessel is one of the speediest, and they were able to gain on us from the start. Slowly they drew up until the border of the twilight zone was reached. Then as we entered under the clouds we were swallowed from the sight of all except Juba. But for his wonderful eyes, there would have been no hope of continuing the chase. He had lived all his life in a land of darkness and now he began to feel himself at ... — A Columbus of Space • Garrett P. Serviss
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